The present invention relates to an electric motor operated hand circular saw. In particular, it relates to a hand circular saw which has a base plate and a motor housing turnable relative to the base plate and accommodating an electric motor which has; a drive shaft supporting a circular saw blade, and a pre-slitting abutment for adjusting a pre-slitting position of the saw blade.
Pre-slitting abutments on the hand circular saws serve to prevent a tearing off of the cover layer during pre-slitting in the process of separation of plate-shaped workpieces of wood or the like with a cover sheet composed of synthetic plastic, hard paper and the like, such as, for example, melanine-coated and veneered plates, plywood plates, wood core plywood, etc. The pre-slitting abutment adjusts the insertion depths of the saw blade into the surface of the workpiece by approximately 1-2 mm., so that in a first working step, only the surface is slitted and, for example, only the cover layer is separated, while in the subsequent sawing step in which the insertion depth of the saw blade is substantially 5 mm. greater than the workpiece thickness, the workpiece can be separated without any tearing off.
In a known hand circular saw of the above-mentioned type disclosed in the German document DE 40 01 331 A1, the pre-slitting abutment is formed as a turning lever which is turnable on the saw blade protective hood fixedly connected with the base plate and is limitedly adjustable in a vertical direction in a longitudinal hole. It is pulled by a pulling screen mounted on the protective hood in the direction of the protective hood, until it abuts against an abutment provided there. An abutment element is connected with the motor housing and during insertion of the saw blade in its pre-slitting position, abuts against an abutment projection of the turning lever. After performing the pre-slitting step, the turning lever is turned against the restoring force of the pulling spring and the motor housing of the saw blade can be turned to a desired cutting depth. A presumption for performing the pre-slitting step is, however, the use of a guiding rail with a sliding shoe mounted on the base plate and sliding on a guiding rib which projects over the guiding rail fixedly clamped on the surface of the workpiece.